Građevinski fakultet - BIM2Ψ

Obrisani Korisnik — Wed, 14 Oct 2026 11:21:18 GMT

Hrvatski
English

BIM2Ψ · Institucionalni istraživački projekt

Razvoj metode za kvantificiranje toplinskih mostova na temelju reprezentativnih presjeka iz 3D BIM modela

Razvijamo metodu koja iz 3D BIM modela izdvaja reprezentativne presjeke zgrade i iz njih brzo, ponovljivo i u skladu s normama određuje toplinske gubitke kroz toplinske mostove.

NextGenerationEUJačanje konkurentnosti mladih znanstvenikaBroj projekta 100-041/26

Financira Europska unija – NextGenerationEU
Projekt se financira iz Nacionalnog plana oporavka i otpornosti 2021. – 2026.

mjeseci

1. 10. 2025. – 30. 9. 2029.

44.940 €

ukupna vrijednost

Nacionalni plan oporavka i otpornosti

radna paketa

od BIM modela do softvera

partnera

iz Hrvatske, Njemačke, Bugarske i Rumunjske

01 · O projektu

Zašto toplinski mostovi?

Toplinski mostovi su mjesta na kojima je prekinut kontinuitet toplinske izolacije – spojevi balkona, međukatnih ploča, krova i prozora sa zidom. U zgradama gotovo nulte energije (nZEB) i zgradama nulte emisije (ZEB), u kojima su ostali gubici svedeni na minimum, njihov udio u transmisijskim gubicima postaje velik.

Ipak, u praksi se rijetko proračunavaju detaljno: numerički proračun prema normi HRN EN ISO 10211 zahtijeva ručno modeliranje svakog detalja, pa se najčešće koriste pojednostavljene vrijednosti iz normi i atlasa toplinskih mostova.

Cilj projekta BIM2Ψ je razviti i potvrditi metodu koja ukupne gubitke kroz toplinske mostove određuje iz ograničenog broja reprezentativnih horizontalnih i vertikalnih presjeka izdvojenih iz 3D BIM modela.

Energija i klima

Prema Direktivi (EU) 2024/1275 sve nove zgrade od 2030. moraju biti zgrade nulte emisije – to zahtijeva precizan proračun svih gubitaka kroz ovojnicu.

Zdravlje i trajnost

Niske temperature unutarnjih površina na spojevima uzrokuju kondenzaciju i plijesan, osobito u višestambenim zgradama u kojima se detalji ponavljaju.

Projektantska praksa

Automatizacija iz BIM modela zamjenjuje dugotrajno ručno modeliranje i smanjuje subjektivnost pri odabiru detalja.

Ilustrativni 2D proračun spoja balkonske ploče i zida s ETICS sustavom prema HRN EN ISO 10211 (softver CRORAL, vanjska temperatura −5 °C).

−83 %

manji linijski koeficijent prolaska topline Ψ uz element za prekid toplinskog mosta

+3,3 °C

viša najniža temperatura unutarnje površine (15,4 → 18,7 °C)

02 · Metoda

Od BIM modela do gubitaka kroz toplinske mostove

Umjesto zasebnog modeliranja svakog spoja, metoda iz BIM modela izdvaja ograničen broj karakterističnih presjeka koji obuhvaćaju cijelu vanjsku ovojnicu, proračunava ih numerički i iz rezultata određuje ukupne gubitke zgrade.

Korak 1

3D BIM model

Model zgrade (IFC) s geometrijom, slojevima ovojnice i svojstvima materijala.

Korak 2

Reprezentativni presjeci

Izdvajanje horizontalnih i vertikalnih presjeka s ulaznim podacima o materijalima.

Korak 3

2D numerički proračun

Temperaturno polje i Ψ-vrijednosti prema HRN EN ISO 10211 u alatu CRORAL.

H_tr,TB = Σ Ψ_k·l_k

Korak 4

Gubici zgrade

Ukupni transmisijski gubici kroz toplinske mostove zgrade iz rezultata presjeka.

Ciljana točnost metode: odstupanje do ±2 % u odnosu na detaljne referentne modele.

Radni paketi

RP1Priprema BIM modela i odabir reprezentativnih zgrada

Odabir višestambenih zgrada različite tipologije, katnosti i konstruktivnih sustava; izrada detaljnih 3D BIM modela s definiranim slojevima vanjske ovojnice i svojstvima materijala; uspostava baze presjeka za daljnju obradu.

RP2Automatizacija izdvajanja presjeka i ulaznih podataka

Integracija s BIM platformama koje podržavaju API pristup ili vlastiti algoritmi za izdvajanje horizontalnih i vertikalnih presjeka s podacima o slojevima i toplinskim svojstvima materijala (npr. konverzijom IFC u DXF), uz Python i JavaScript.

RP3Numerički proračuni i validacija metode

Izrada 2D numeričkih modela prema HRN EN ISO 10211 u alatu CRORAL, proračun Ψ-vrijednosti i razvoj metodologije za procjenu ukupnih gubitaka H_tr,TB iz ograničenog broja presjeka; provjera usporedbom s referentnim modelima.

RP4Nadogradnja CRORAL-a ili razvoj novog alata

Softver za automatski izračun Ψ-vrijednosti, procjenu H_tr,TB i izradu izvještaja u skladu s normama; radionice s projektantima i pilot testiranja na stvarnim projektima.

03 · Plan rada

Četiri godine provedbe

1. godina

2025./2026.

Završeno

Nabava literature i opreme
Istraživački rad i prikupljanje podataka
Odabir i BIM modeliranje zgrada
Upravljanje i izvještavanje

2. godina

2026./2027.

U tijeku

BIM modeliranje (nastavak)
Algoritam za izdvajanje presjeka
Numerički proračuni i validacija
Znanstveni boravak u inozemstvu
Usavršavanja tima
Znanstveni skupovi

3. godina

2027./2028.

Planirano

Algoritam i validacija (nastavak)
Razvoj i testiranje softvera
Usklađivanje s EU normama
Objava znanstvenih radova
Znanstveni skupovi

4. godina

2028./2029.

Planirano

Razvoj i testiranje softvera
Pilot testiranja i radionice
Završna evaluacija
Prijava na Horizon Europe
Objava znanstvenih radova

Proteklo vrijeme provedbe25 % · stanje: listopad 2026.

04 · Napredak

Prva godina provedbe

U prvoj godini (1. 10. 2025. – 30. 9. 2026.) postavljeni su temelji za razvoj metode.

Nabavljena je računalna i programska oprema za numeričke proračune i razvoj algoritama.

Analizirana je struktura IFC modela (IFC2x3 i IFC4): geometrija ovojnice, višeslojni sastavi i svojstva materijala potrebna za toplinski proračun.

Pripremljeni su prvi BIM modeli zgrada za razvoj i provjeru tijeka podataka.

Proračunska jezgra CRORAL verificirana je na normativnim primjerima HRN EN ISO 10211 i HRN EN ISO 10077-2 – svi primjeri zadovoljavaju kriterije normi.

BIM modeli pripremljeni u prvoj godini

BIM model stambene zgrade s ravnim krovom i balkonom (Archicad → IFC)

BIM model stambene zgrade s kosim krovom (Archicad → IFC)

Testni IFC model dvoetažne zgrade s poznatim svojstvima materijala za kontroliranu provjeru tijeka podataka

Verifikacija proračunske jezgre

Referentni slučaj 2 iz HRN EN ISO 10211: sve izračunate temperature u točkama A–I unutar su dopuštenog odstupanja od ±0,1 K, a toplinski tok iznosi 9,48 W/m (norma: 9,5 ± 0,1 W/m).

05 · Tim

Istraživački tim

dr. sc. Mergim Gaši

voditelj projekta

Građevinski fakultet, Zavod za materijale

Energetska učinkovitost zgrada, toplinski mostovi i BIM; autor softvera CRORAL.

Profil CroRIS ORCID

Domagoj Tkalčić

asistent – doktorand

Građevinski fakultet

BIM modeliranje i proračun toplinskih mostova; razvoj metode i validacija rezultata.

Profil CroRIS

dr. sc. Matea Flegar Pregernik

viša asistentica

Građevinski fakultet

Energetska učinkovitost i LCA analiza; numerički proračuni i usporedba nove i klasične metode.

Profil CroRIS

dr. sc. Filip Zorić

direktor

Crobotic Solutions d.o.o.

Algoritmi za obradu BIM podataka i programsko sučelje; transfer znanja i tehnologije.

CroRIS

dr. sc. Marina Bagarić

product manager

Wienerberger d.o.o.

Vanjska ovojnica zgrade i energetska učinkovitost; validacija metode i interpretacija rezultata.

CroRIS

06 · Partneri

Suradnja s gospodarstvom i znanstvenim ustanovama

Projekt podupire osam organizacija koje su potpisale pisma namjere o suradnji – u testiranju metode, korištenju rezultata i daljnjem razvoju alata.

Crobotic Solutions d.o.o.

Zagreb, Hrvatska

tehnološki startup

Wienerberger d.o.o.

Hrvatska

građevni materijali

Knauf Insulation d.o.o.

Novi Marof, Hrvatska

toplinska izolacija

Baldinistudio d.o.o.

Hrvatska

projektantski ured

Energetski institut Hrvoje Požar

Zagreb, Hrvatska

znanstveni institut

TU Darmstadt

Darmstadt, Njemačka

Institut für Werkstoffe im Bauwesen

Center for Energy Efficiency EnEffect

Sofija, Bugarska

centar za energetsku učinkovitost

Cluster Pro-nZEB

Rumunjska

klaster za zgrade gotovo nulte energije

Projekt podržava i prof. dr. sc. Boris Trogrlić, nositelj kolegija Fizika zgrade na Fakultetu građevinarstva, arhitekture i geodezije u Splitu.

07 · Rezultati

Rezultati i diseminacija

Znanstveni radovi, izlaganja na konferencijama i ostali rezultati projekta objavljivat će se na ovoj stranici. Ciljevi do kraja projekta:

znanstvena rada u časopisima WoS/Scopus

izlaganja na međunarodnim konferencijama

≥15

reprezentativnih presjeka iz BIM modela

tipologije zgrada za validaciju metode

≥2

verzije softverskog alata testirane u praksi

≥5

projektanata u radionicama i testiranju

znanstveni boravak u inozemstvu

aktivnosti popularizacije znanosti

Publikacije

Prvi radovi proizašli iz projekta očekuju se u 3. i 4. godini provedbe.

08 · Kontakt

Kontakt

Voditelj projekta

dr. sc. Mergim Gaši

mergim.gasi@grad.unizg.hr

Sveučilište u Zagrebu Građevinski fakultet
Zavod za materijale
Fra Andrije Kačića-Miošića 26, 10000 Zagreb

Projekt se financira iz Nacionalnog plana oporavka i otpornosti 2021. – 2026. (NextGenerationEU, izvor 581 – Mehanizam za oporavak i otpornost) u okviru Poziva za financiranje institucionalnih istraživačkih projekata Sveučilišta u Zagrebu Građevinskog fakulteta, projektna linija Jačanje konkurentnosti mladih znanstvenika.

Financira Europska unija – NextGenerationEU. Izneseni stavovi i mišljenja samo su autorova i ne odražavaju nužno službena stajališta Europske unije ili Europske komisije. Ni Europska unija ni Europska komisija ne mogu se smatrati odgovornima za njih.

BIM2Ψ · Institutional research project

Hrvatska verzija

Development of a Method for Quantifying Thermal Bridges Based on Representative Cross-Sections Extracted from a 3D BIM Model

We are developing a method that extracts representative cross-sections from a 3D BIM model and uses them to determine heat losses through thermal bridges quickly, reproducibly and in line with the standards.

NextGenerationEUStrengthening the competitiveness of young scientistsProject no. 100-041/26

Funded by the European Union – NextGenerationEU
The project is funded by the National Recovery and Resilience Plan 2021–2026.

months

1 Oct 2025 – 30 Sep 2029

€44,940

total budget

National Recovery and Resilience Plan

work packages

from BIM model to software

partners

from Croatia, Germany, Bulgaria and Romania

01 · About

Why thermal bridges?

Thermal bridges are places where the continuity of thermal insulation is interrupted – junctions of balconies, floor slabs, roofs and windows with walls. In nearly zero-energy (nZEB) and zero-emission buildings (ZEB), where all other losses are minimised, their share of transmission heat loss becomes large.

Yet in practice they are rarely calculated in detail: a numerical calculation to EN ISO 10211 requires every detail to be modelled by hand, so designers mostly rely on simplified default values from standards and thermal-bridge atlases.

The aim of BIM2Ψ is to develop and validate a method that determines total thermal-bridge losses from a limited number of representative horizontal and vertical cross-sections extracted from a 3D BIM model.

Energy and climate

Under Directive (EU) 2024/1275 all new buildings must be zero-emission buildings from 2030 – which requires an accurate calculation of every loss through the envelope.

Health and durability

Low internal surface temperatures at junctions lead to condensation and mould, especially in multi-residential buildings where details are repeated many times.

Design practice

Automation from the BIM model replaces time-consuming manual modelling and reduces subjectivity in the choice of details.

Illustrative 2D calculation of a balcony slab through an ETICS-insulated wall to EN ISO 10211 (CRORAL software, outside temperature −5 °C).

−83%

lower linear thermal transmittance Ψ with a thermal-break element

+3.3 °C

higher lowest internal surface temperature (15.4 → 18.7 °C)

02 · Method

From the BIM model to thermal-bridge losses

Instead of modelling every junction separately, the method extracts a limited number of characteristic cross-sections covering the whole building envelope from the BIM model, calculates them numerically and derives the total losses of the building from the results.

Step 1

3D BIM model

Building model (IFC) with geometry, envelope layers and material properties.

Step 2

Representative sections

Extraction of horizontal and vertical sections with material input data.

Step 3

2D numerical calculation

Temperature field and Ψ-values to EN ISO 10211 in the CRORAL tool.

H_tr,TB = Σ Ψ_k·l_k

Step 4

Building losses

Total transmission heat loss through the thermal bridges of the building, from the section results.

Target accuracy of the method: deviation within ±2% of detailed reference models.

Work packages

WP1BIM models and selection of representative buildings

Selection of multi-residential buildings of different typologies, heights and structural systems; detailed 3D BIM models with defined envelope layers and material properties; a database of sections for further processing.

WP2Automated extraction of sections and input data

Integration with BIM platforms offering API access, or in-house algorithms that extract horizontal and vertical sections together with layer and thermal-property data (e.g. via IFC-to-DXF conversion), using Python and JavaScript.

WP3Numerical calculations and validation

2D numerical models to EN ISO 10211 in CRORAL, calculation of Ψ-values and a methodology for estimating the total loss H_tr,TB from a limited number of sections; validation against reference models.

WP4CRORAL upgrade or a new tool

Software for automatic calculation of Ψ-values, estimation of H_tr,TB and standard-compliant reports; workshops with designers and pilot tests on real projects.

03 · Work plan

Four years of implementation

Year 1

2025/2026

Completed

Literature and equipment
Research and data collection
Selection and BIM modelling of buildings
Management and reporting

Year 2

2026/2027

In progress

BIM modelling (continued)
Section-extraction algorithm
Numerical calculations and validation
Research stay abroad
Team training
Scientific conferences

Year 3

2027/2028

Planned

Algorithm and validation (continued)
Software development and testing
Alignment with EU standards
Journal publications
Scientific conferences

Year 4

2028/2029

Planned

Software development and testing
Pilot tests and workshops
Final evaluation
Horizon Europe proposal
Journal publications

Implementation time elapsed25 % · as of October 2026

04 · Progress

First year of implementation

In the first year (1 October 2025 – 30 September 2026) the foundations for the method were laid.

Computing hardware and software for numerical calculations and algorithm development were procured.

The structure of IFC models (IFC2x3 and IFC4) was analysed: envelope geometry, multi-layer assemblies and the material properties needed for thermal calculation.

The first BIM models of buildings were prepared for developing and checking the data flow.

The CRORAL calculation core was verified against the normative examples of EN ISO 10211 and EN ISO 10077-2 – all examples meet the criteria of the standards.

BIM models prepared in the first year

BIM model of a residential building with a flat roof and a balcony (Archicad → IFC)

BIM model of a residential building with a pitched roof (Archicad → IFC)

Test IFC model of a two-storey building with known material properties for a controlled check of the data flow

Verification of the calculation core

Reference case 2 of EN ISO 10211: all calculated temperatures at points A–I are within the permitted deviation of ±0.1 K, and the heat flow is 9.48 W/m (standard: 9.5 ± 0.1 W/m).

05 · Team

Research team

Mergim Gaši, PhD

principal investigator

Faculty of Civil Engineering, Department of Materials

Energy efficiency of buildings, thermal bridges and BIM; author of the CRORAL software.

Profile CroRIS ORCID

Domagoj Tkalčić

assistant, PhD candidate

Faculty of Civil Engineering

BIM modelling and thermal-bridge calculation; method development and validation of results.

Profile CroRIS

Matea Flegar Pregernik, PhD

senior assistant

Faculty of Civil Engineering

Energy efficiency and LCA; numerical calculations and comparison of the new and the classical method.

Profile CroRIS

Filip Zorić

CEO, PhD candidate at FER

Crobotic Solutions d.o.o.

Algorithms for BIM data processing and the software interface; knowledge and technology transfer.

CroRIS

Marina Bagarić, PhD

product manager

Wienerberger d.o.o.

Building envelope and energy efficiency; validation of the method and interpretation of results.

CroRIS

06 · Partners

Collaboration with industry and research institutions

The project is supported by eight organisations that signed letters of intent – for testing the method, using the results and further developing the tool.

Crobotic Solutions d.o.o.

Zagreb, Croatia

technology start-up

Wienerberger d.o.o.

Croatia

building materials

Knauf Insulation d.o.o.

Novi Marof, Croatia

thermal insulation

Baldinistudio d.o.o.

Croatia

design office

Energy Institute Hrvoje Požar

Zagreb, Croatia

research institute

TU Darmstadt

Darmstadt, Germany

Institut für Werkstoffe im Bauwesen

Center for Energy Efficiency EnEffect

Sofia, Bulgaria

energy efficiency centre

Cluster Pro-nZEB

Romania

nearly zero-energy buildings cluster

The project is also supported by Prof. Boris Trogrlić, PhD, who teaches Building Physics at the Faculty of Civil Engineering, Architecture and Geodesy in Split.

07 · Results

Results and dissemination

Journal papers, conference presentations and other project results will be published on this page. Targets by the end of the project:

journal papers (WoS/Scopus)

presentations at international conferences

≥15

representative sections from BIM models

building typologies for validation

≥2

software versions tested in practice

≥5

designers in workshops and testing

research stay abroad

science outreach activities

Publications

The first papers resulting from the project are expected in years 3 and 4.

08 · Contact

Contact

Principal investigator

Mergim Gaši, PhD

mergim.gasi@grad.unizg.hr

University of Zagreb, Faculty of Civil Engineering
Department of Materials
Fra Andrije Kačića-Miošića 26, 10000 Zagreb, Croatia

The project is funded by the National Recovery and Resilience Plan 2021–2026 (NextGenerationEU, source 581 – Recovery and Resilience Facility) under the Call for Funding of Institutional Research Projects of the University of Zagreb Faculty of Civil Engineering, project line Strengthening the Competitiveness of Young Scientists.

Funded by the European Union – NextGenerationEU. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Commission. Neither the European Union nor the European Commission can be held responsible for them.

Obrisani Korisnik — Wed, 07 Oct 2026 09:01:56 GMT

Hrvatski
English

BIM2Ψ · Institucionalni istraživački projekt

English version

Razvoj metode za kvantificiranje toplinskih mostova na temelju reprezentativnih presjeka iz 3D BIM modela

Razvijamo metodu koja iz 3D BIM modela izdvaja reprezentativne presjeke zgrade i iz njih brzo, ponovljivo i u skladu s normama određuje toplinske gubitke kroz toplinske mostove.

NextGenerationEUJačanje konkurentnosti mladih znanstvenikaBroj projekta 100-041/26

Financira Europska unija – NextGenerationEU
Projekt se financira iz Nacionalnog plana oporavka i otpornosti 2021. – 2026.

mjeseci

1. 10. 2025. – 30. 9. 2029.

44.940 €

ukupna vrijednost

Nacionalni plan oporavka i otpornosti

radna paketa

od BIM modela do softvera

partnera

iz Hrvatske, Njemačke, Bugarske i Rumunjske

01 · O projektu

Zašto toplinski mostovi?

Energija i klima

Prema Direktivi (EU) 2024/1275 sve nove zgrade od 2030. moraju biti zgrade nulte emisije – to zahtijeva precizan proračun svih gubitaka kroz ovojnicu.

Zdravlje i trajnost

Niske temperature unutarnjih površina na spojevima uzrokuju kondenzaciju i plijesan, osobito u višestambenim zgradama u kojima se detalji ponavljaju.

Projektantska praksa

Automatizacija iz BIM modela zamjenjuje dugotrajno ručno modeliranje i smanjuje subjektivnost pri odabiru detalja.

Ilustrativni 2D proračun spoja balkonske ploče i zida s ETICS sustavom prema HRN EN ISO 10211 (softver CRORAL, vanjska temperatura −5 °C).

−83 %

manji linijski koeficijent prolaska topline Ψ uz element za prekid toplinskog mosta

+3,3 °C

viša najniža temperatura unutarnje površine (15,4 → 18,7 °C)

02 · Metoda

Od BIM modela do gubitaka kroz toplinske mostove

Korak 1

3D BIM model

Model zgrade (IFC) s geometrijom, slojevima ovojnice i svojstvima materijala.

Korak 2

Reprezentativni presjeci

Izdvajanje horizontalnih i vertikalnih presjeka s ulaznim podacima o materijalima.

Korak 3

2D numerički proračun

Temperaturno polje i Ψ-vrijednosti prema HRN EN ISO 10211 u alatu CRORAL.

H_tr,TB = Σ Ψ_k·l_k

Korak 4

Gubici zgrade

Ukupni transmisijski gubici kroz toplinske mostove zgrade iz rezultata presjeka.

Ciljana točnost metode: odstupanje do ±2 % u odnosu na detaljne referentne modele.

Radni paketi

RP1Priprema BIM modela i odabir reprezentativnih zgrada

RP2Automatizacija izdvajanja presjeka i ulaznih podataka

RP3Numerički proračuni i validacija metode

RP4Nadogradnja CRORAL-a ili razvoj novog alata

Softver za automatski izračun Ψ-vrijednosti, procjenu H_tr,TB i izradu izvještaja u skladu s normama; radionice s projektantima i pilot testiranja na stvarnim projektima.

03 · Plan rada

Četiri godine provedbe

1. godina

2025./2026.

Završeno

Nabava literature i opreme
Istraživački rad i prikupljanje podataka
Odabir i BIM modeliranje zgrada
Upravljanje i izvještavanje

2. godina

2026./2027.

U tijeku

BIM modeliranje (nastavak)
Algoritam za izdvajanje presjeka
Numerički proračuni i validacija
Znanstveni boravak u inozemstvu
Usavršavanja tima
Znanstveni skupovi

3. godina

2027./2028.

Planirano

Algoritam i validacija (nastavak)
Razvoj i testiranje softvera
Usklađivanje s EU normama
Objava znanstvenih radova
Znanstveni skupovi

4. godina

2028./2029.

Planirano

Razvoj i testiranje softvera
Pilot testiranja i radionice
Završna evaluacija
Prijava na Horizon Europe
Objava znanstvenih radova

Proteklo vrijeme provedbe25 % · stanje: listopad 2026.

04 · Napredak

Prva godina provedbe

U prvoj godini (1. 10. 2025. – 30. 9. 2026.) postavljeni su temelji za razvoj metode.

Nabavljena je računalna i programska oprema za numeričke proračune i razvoj algoritama.

Analizirana je struktura IFC modela (IFC2x3 i IFC4): geometrija ovojnice, višeslojni sastavi i svojstva materijala potrebna za toplinski proračun.

Pripremljeni su prvi BIM modeli zgrada za razvoj i provjeru tijeka podataka.

Proračunska jezgra CRORAL verificirana je na normativnim primjerima HRN EN ISO 10211 i HRN EN ISO 10077-2 – svi primjeri zadovoljavaju kriterije normi.

BIM modeli pripremljeni u prvoj godini

BIM model stambene zgrade s ravnim krovom i balkonom (Archicad → IFC)

BIM model stambene zgrade s kosim krovom (Archicad → IFC)

Testni IFC model dvoetažne zgrade s poznatim svojstvima materijala za kontroliranu provjeru tijeka podataka

Verifikacija proračunske jezgre

Referentni slučaj 2 iz HRN EN ISO 10211: sve izračunate temperature u točkama A–I unutar su dopuštenog odstupanja od ±0,1 K, a toplinski tok iznosi 9,48 W/m (norma: 9,5 ± 0,1 W/m).

05 · Tim

Istraživački tim

dr. sc. Mergim Gaši

voditelj projekta

Građevinski fakultet, Zavod za materijale

Energetska učinkovitost zgrada, toplinski mostovi i BIM; autor softvera CRORAL.

Profil CroRIS ORCID

Domagoj Tkalčić

asistent – doktorand

Građevinski fakultet

BIM modeliranje i proračun toplinskih mostova; razvoj metode i validacija rezultata.

Profil CroRIS

dr. sc. Matea Flegar Pregernik

viša asistentica

Građevinski fakultet

Energetska učinkovitost i LCA analiza; numerički proračuni i usporedba nove i klasične metode.

Profil CroRIS

Filip Zorić

direktor, doktorand FER-a

Crobotic Solutions d.o.o.

Algoritmi za obradu BIM podataka i programsko sučelje; transfer znanja i tehnologije.

CroRIS

dr. sc. Marina Bagarić

product manager

Wienerberger d.o.o.

Vanjska ovojnica zgrade i energetska učinkovitost; validacija metode i interpretacija rezultata.

CroRIS

06 · Partneri

Suradnja s gospodarstvom i znanstvenim ustanovama

Projekt podupire osam organizacija koje su potpisale pisma namjere o suradnji – u testiranju metode, korištenju rezultata i daljnjem razvoju alata.

Crobotic Solutions d.o.o.

Zagreb, Hrvatska

tehnološki startup

Wienerberger d.o.o.

Hrvatska

građevni materijali

Knauf Insulation d.o.o.

Novi Marof, Hrvatska

toplinska izolacija

Baldinistudio d.o.o.

Hrvatska

projektantski ured

Energetski institut Hrvoje Požar

Zagreb, Hrvatska

znanstveni institut

Technische Universität Darmstadt

Darmstadt, Njemačka

Institut für Werkstoffe im Bauwesen

Center for Energy Efficiency EnEffect

Sofija, Bugarska

centar za energetsku učinkovitost

Cluster Pro-nZEB

Rumunjska

klaster za zgrade gotovo nulte energije

Projekt podržava i prof. dr. sc. Boris Trogrlić, nositelj kolegija Fizika zgrade na Fakultetu građevinarstva, arhitekture i geodezije u Splitu.

07 · Rezultati

Rezultati i diseminacija

Znanstveni radovi, izlaganja na konferencijama i ostali rezultati projekta objavljivat će se na ovoj stranici. Ciljevi do kraja projekta:

znanstvena rada u časopisima WoS/Scopus

izlaganja na međunarodnim konferencijama

≥15

reprezentativnih presjeka iz BIM modela

tipologije zgrada za validaciju metode

≥2

verzije softverskog alata testirane u praksi

≥5

projektanata u radionicama i testiranju

znanstveni boravak u inozemstvu

aktivnosti popularizacije znanosti

Publikacije

Prvi radovi proizašli iz projekta očekuju se u 3. i 4. godini provedbe.

08 · Kontakt

Kontakt

Voditelj projekta

dr. sc. Mergim Gaši

mergim.gasi@grad.unizg.hr

Sveučilište u Zagrebu Građevinski fakultet
Zavod za materijale
Fra Andrije Kačića-Miošića 26, 10000 Zagreb

BIM2Ψ · Institutional research project

Hrvatska verzija

Development of a Method for Quantifying Thermal Bridges Based on Representative Cross-Sections Extracted from a 3D BIM Model

NextGenerationEUStrengthening the competitiveness of young scientistsProject no. 100-041/26

Funded by the European Union – NextGenerationEU
The project is funded by the National Recovery and Resilience Plan 2021–2026.

months

1 Oct 2025 – 30 Sep 2029

€44,940

total budget

National Recovery and Resilience Plan

work packages

from BIM model to software

partners

from Croatia, Germany, Bulgaria and Romania

01 · About

Why thermal bridges?

Energy and climate

Under Directive (EU) 2024/1275 all new buildings must be zero-emission buildings from 2030 – which requires an accurate calculation of every loss through the envelope.

Health and durability

Low internal surface temperatures at junctions lead to condensation and mould, especially in multi-residential buildings where details are repeated many times.

Design practice

Automation from the BIM model replaces time-consuming manual modelling and reduces subjectivity in the choice of details.

Illustrative 2D calculation of a balcony slab through an ETICS-insulated wall to EN ISO 10211 (CRORAL software, outside temperature −5 °C).

−83%

lower linear thermal transmittance Ψ with a thermal-break element

+3.3 °C

higher lowest internal surface temperature (15.4 → 18.7 °C)

02 · Method

From the BIM model to thermal-bridge losses

Step 1

3D BIM model

Building model (IFC) with geometry, envelope layers and material properties.

Step 2

Representative sections

Extraction of horizontal and vertical sections with material input data.

Step 3

2D numerical calculation

Temperature field and Ψ-values to EN ISO 10211 in the CRORAL tool.

H_tr,TB = Σ Ψ_k·l_k

Step 4

Building losses

Total transmission heat loss through the thermal bridges of the building, from the section results.

Target accuracy of the method: deviation within ±2% of detailed reference models.

Work packages

WP1BIM models and selection of representative buildings

WP2Automated extraction of sections and input data

WP3Numerical calculations and validation

2D numerical models to EN ISO 10211 in CRORAL, calculation of Ψ-values and a methodology for estimating the total loss H_tr,TB from a limited number of sections; validation against reference models.

WP4CRORAL upgrade or a new tool

Software for automatic calculation of Ψ-values, estimation of H_tr,TB and standard-compliant reports; workshops with designers and pilot tests on real projects.

03 · Work plan

Four years of implementation

Year 1

2025/2026

Completed

Literature and equipment
Research and data collection
Selection and BIM modelling of buildings
Management and reporting

Year 2

2026/2027

In progress

BIM modelling (continued)
Section-extraction algorithm
Numerical calculations and validation
Research stay abroad
Team training
Scientific conferences

Year 3

2027/2028

Planned

Algorithm and validation (continued)
Software development and testing
Alignment with EU standards
Journal publications
Scientific conferences

Year 4

2028/2029

Planned

Software development and testing
Pilot tests and workshops
Final evaluation
Horizon Europe proposal
Journal publications

Implementation time elapsed25 % · as of October 2026

04 · Progress

First year of implementation

In the first year (1 October 2025 – 30 September 2026) the foundations for the method were laid.

Computing hardware and software for numerical calculations and algorithm development were procured.

The structure of IFC models (IFC2x3 and IFC4) was analysed: envelope geometry, multi-layer assemblies and the material properties needed for thermal calculation.

The first BIM models of buildings were prepared for developing and checking the data flow.

The CRORAL calculation core was verified against the normative examples of EN ISO 10211 and EN ISO 10077-2 – all examples meet the criteria of the standards.

BIM models prepared in the first year

BIM model of a residential building with a flat roof and a balcony (Archicad → IFC)

BIM model of a residential building with a pitched roof (Archicad → IFC)

Test IFC model of a two-storey building with known material properties for a controlled check of the data flow

Verification of the calculation core

Reference case 2 of EN ISO 10211: all calculated temperatures at points A–I are within the permitted deviation of ±0.1 K, and the heat flow is 9.48 W/m (standard: 9.5 ± 0.1 W/m).

05 · Team

Research team

Mergim Gaši, PhD

principal investigator

Faculty of Civil Engineering, Department of Materials

Energy efficiency of buildings, thermal bridges and BIM; author of the CRORAL software.

Profile CroRIS ORCID

Domagoj Tkalčić

assistant, PhD candidate

Faculty of Civil Engineering

BIM modelling and thermal-bridge calculation; method development and validation of results.

Profile CroRIS

Matea Flegar Pregernik, PhD

senior assistant

Faculty of Civil Engineering

Energy efficiency and LCA; numerical calculations and comparison of the new and the classical method.

Profile CroRIS

Filip Zorić

CEO, PhD candidate at FER

Crobotic Solutions d.o.o.

Algorithms for BIM data processing and the software interface; knowledge and technology transfer.

CroRIS

Marina Bagarić, PhD

product manager

Wienerberger d.o.o.

Building envelope and energy efficiency; validation of the method and interpretation of results.

CroRIS

06 · Partners

Collaboration with industry and research institutions

The project is supported by eight organisations that signed letters of intent – for testing the method, using the results and further developing the tool.

Crobotic Solutions d.o.o.

Zagreb, Croatia

technology start-up

Wienerberger d.o.o.

Croatia

building materials

Knauf Insulation d.o.o.

Novi Marof, Croatia

thermal insulation

Baldinistudio d.o.o.

Croatia

design office

Energy Institute Hrvoje Požar

Zagreb, Croatia

research institute

Technische Universität Darmstadt

Darmstadt, Germany

Institut für Werkstoffe im Bauwesen

Center for Energy Efficiency EnEffect

Sofia, Bulgaria

energy efficiency centre

Cluster Pro-nZEB

Romania

nearly zero-energy buildings cluster

The project is also supported by Prof. Boris Trogrlić, PhD, who teaches Building Physics at the Faculty of Civil Engineering, Architecture and Geodesy in Split.

07 · Results

Results and dissemination

Journal papers, conference presentations and other project results will be published on this page. Targets by the end of the project:

journal papers (WoS/Scopus)

presentations at international conferences

≥15

representative sections from BIM models

building typologies for validation

≥2

software versions tested in practice

≥5

designers in workshops and testing

research stay abroad

science outreach activities

Publications

The first papers resulting from the project are expected in years 3 and 4.

08 · Contact

Contact

Principal investigator

Mergim Gaši, PhD

mergim.gasi@grad.unizg.hr

University of Zagreb, Faculty of Civil Engineering
Department of Materials
Fra Andrije Kačića-Miošića 26, 10000 Zagreb, Croatia